Recent United States Federal, State and Local legislation regarding the "Montreal Protocol" prohibiting intentional release or venting of chlorofluorocarbons and hydrochlorofluorocarbons into the atmosphere has prompted the development of a process capable of recovering refrigerant from a refrigeration system, filtering contaminants, and returning the refrigerant to the refrigeration system after repairs are made.
Such recovery systems are typically comprised of a refrigerant piston-type compressor to create a reduced pressure in order to transfer the refrigerant from the refrigeration system to a storage vessel and representative patents are U.S. Pat. Nos. 3,744,273 to C. D. Ware, 4,367,637 to H. Paulokat, 4,554,792 to A. Margulefsky et al, 4,766,733 to C. J. Scuderi, 5,022,230 to J. J. Todack, 5,077,984 to J. H. Vance and 5,123,259 to E. C. Morgan, Sr. Other commercially available systems require some type of pump or compressor for refrigerant recovery thereby resulting in a high initial cost, high maintenance costs, poor portability and require electrical power to be available at the site of use. Moreover, recovery systems which employ compressors are susceptible to contaminants from the refrigerants they are recovering, cannot tolerate liquid refrigerant and suffer from compressor lubricant deprivation when their lubricant goes into solution with the recovered refrigerant resulting in a rapidly reduced "reclaim system" life and costly repairs.
It has been proposed to employ a refrigerant recovery system which eliminates the use of pumps or compressors. For example, U.S. Pat. No. 5,101,637 to B. E. Daily discloses a system comprised of a cryogenic container for either a liquid nitrogen or carbon dioxide composition which is capable of being vented to the atmosphere and which, when it volatilizes in a coil, will reduce the pressure in a separate storage cylinder surrounded by the coil. When the pressure is reduced in the container, it will remove the refrigerant from the refrigerant system as a result of pressure differential and, as the refrigerant condenses in the storage container, will continue to draw more refrigerant into that container. The use of a separate cryogenic container and associated plumbing is costly and reduces portability of the device; and, as a practical matter, in using carbon dioxide would require vaporization of that composition before it can be transferred in the form of sensible heat to the coil surrounding the storage vessel and therefore would increase the chill time. Furthermore, the use of an evaporator coil around the storage vessel will produce an air gap which tends to reduce the thermal transfer to the storage vessel and increase the chill time; nor does the system allow for overfilling of the storage container.
It is proposed in accordance with the present invention to provide a lightweight, portable recovery system which, among other features, employs a readily available, consumable heat sink for removal of the refrigerant from an abandoned or operating refrigerant unit with minimum chill time and in such a way as to avoid the use of electrical power, mechanical pumps or compressors as well as extensive plumbing.